Tube furnace provided with filling bodies



March 4, 1969 J. SELLIN 3,

TUBE FURNACE PROVIDED WITH FILLING BODIES Filed July 12, 1965 511861. Of 2 1 nil J I March 4, 1959 J. SELLIN 3,431,082

TUBE FURNACE PROVIDED WITH FILLING BODIES Filed July 12, 1965 Sheet 2 of 2 Fig.6 2. I

United States Patent 5 94,051 US. Cl. 23-477 Int. (:1. F233 3/00 27 Claims ABSTRACT OF THE DISCLOSURE There is disclosed in reaction apparatus tubes for tube furnaces provided with filling bodies. A vertically arranged outer tube has an axially extending concentrically arranged inner tube whose latter outer wall is spaced from the inner wall of the outer tube. This provides for counterflow, however, there may be in place of the inner tube a rod member extending axially within the outer tube. Filling bodies are supported from the inner tube or the rod. In one form carrier elements in the form of uniformly spaced apart radially extending pins are welded at one end to the outer surface of the inner tube or rod. In another form shelf-like members extending in uniform spaced apart radial direction are secured to the outer surface of the inner tube or rod. In the case of the pins, the filling bodies have an aperture therethrough and they are slidably received on the pins. These filling bodies may be annular with oppositely extending frustrum of a cone ends and two may be pushed onto a carrier pin. The outer bodies in -a radial direction have a greater diameter so that the intervals between the individual filling bodies in the peripheral direction remain approximately equal. In the concept where the carriers are shelf-like members arranged in a uniform geometrical manner, the filling bodies are freely supported. The filling bodies here may take the shape of generally cylindrical members. The filling bodies in all cases are held in position with respect to each other in a uniform predetermined arrangement whereby equal flow conditions exist at all points within the tube and the Weight of the filling bodies is carried by the respective carrier elements.

This invention relates to tubes for tube furnaces, provided with filling bodies.

Tubes which contain a so-called stationary bed of filling bodies are frequently used in chemical work. The filling bodies can here frequently fulfill a plurality of functions at the same time and possess for example an absorbing, flow-guiding, heat-storing or even catalytic action. Moreover in the course of time numberless variants have been developed as regards their outer form and also as regards their material composition. Generally, fragments, balls, tablets or rings are used as tube filling bodies.

The arrangement of the filling bodies can influence very substantially the course of a process and must be determined for example according to the desired speeds of through-flow, sojourn times, heat-storage values, catalyst surfaces and the like.

The manner of the arrangement of the filling bodies has a particular influence upon the mechanical stressing of the tube walls and any installations thereupon and upon the filling bodies themselves. If the filling bodies are introduced by free pouring, which is almost always the case in tubes with relatively small diameter, additional stresses of the tube walls occur as considerable horizontal forces are exerted upon the tube walls as a result of the heaping angle of the bulk material being poured. Moreover the lower filling bodies are considerably stressed by the weight of the upper filling bodies and cannot carry out without hindrance, movements caused by temperature differences. These difficulties naturally become greater with greater pouring heights, narrower tubes and greater more frequent temperature fluctuations. The ratio of the tube diameter to the filling body diameter also plays a substantial part here.

As a result of the movements occurring at every change of temperature, the filling body bed does not remain in the original condition, but the loosely poured-in filling bodies gradually slip more tightly together and in doing so jam themselves against one another and against the tube walls or other installations in such manner that finally no expansion is possible at all any more within the bulk of filling bodies, because a rigid pack of filling bodies has formed. On subsequently occurring temperature changes then a widening of the tube walls occurs or the original filling bodies, mostly provided with cavities, are shattered and impacted and thus lose their original properties. In the case of frequent temperature changes the abovedescribed phenomena can lead to the destruction of the tube wall.

The agglomeration of the filling bodies here firstly considerably falsifies the course of the process in the reaction tube and finally can completely suppress it, if the pressure loss occurring in the caked filling body mass exceeds the acceptable amount.

The above-described phenomena are naturally especially serious in the case of installations which work in a cyclic manner, in which for example the entire filling body masses are heated up to 400 C. temperature difference and cooled down again at intervals of a few minutes, while in such processes highly sensitive catalyst filling bodies which are especially liable to the above explained destruction process are frequently needed. In such installations therefore it is necessary to replace the entire catalyst filling body material at relatively short intervals of time or to sift out the broken down material produced and to replace it by new catalyst material. The expense for working time and catalyst material occurring here and the cessation of production involved in this work are extraordinarily high in tube furnaces used for such processes, and decisively determine the economy of the entire process.

Constructions have already become known which are designed to provide a remedy as regards the abovedescribed disadvantages. Thus it is already known to provide a series of intermediate floors on each of which a layer of filling bodies is arranged. The above-explained difficulties are in fact diminished by this, but still remain fundamentally in existance, apart from the fact that the introduction and the replacement of the filling bodies causes considerable difficulties where such intermediate floors are used, especially in the case of narrow tube crosssections.

Furthermore it is already known to 'apply filling bodies or catalysts as a coating upon the inner Wall of the tube, or to combine individual catalyst filling bodies with the inner wall of the tube, for example by baking-in. However this method involves a very expensive tube production process and moreover is applicable only in the case of relatively small tube diameters or ring gaps where counter-current tubes are used, since otherwise the main quantities of gas passing in the middle are not adequately influenced by the catalysts seated only in or on the tube wall. The method is also not usable in the case of higher working pressures in the tube, on account of the diminution of catalytic effectiveness of the tube due to the embedding of filling bodies.

It has also been proposed to make the filling material elastically yieldable, by mixing the filling bodies with steel springs of special shaping. The filling bodies were then arranged in small steel cages and perforated oblique slideways were provided in the filling body layer, upon which the filling bodies were to be pushed back by the tube walls on cooling and contraction thereof. However, this method has not proved satisfactory. The steel springs mixed with the filling bodies lose their elasticity at higher working temperatures. The cage inserts are also deformed after a relatively short working time and the proposed slideways distort under the temperature stress so that they do not fulfill their intended functions.

Finally it is already known to interpose short additional tube pieces between filling body layers and tube wall, in order to render movement possible between the filling bodies and the tube wall on temperature change, without stressing of the tube wall. These additional tube sections however cannot prevent the destruction of the filling bodies and considerably impair thermal transmission through the tube walls and therefore are not usable especially for tubes with smaller diameter and for processes with supply or withdrawal of heat through the tube wall.

In order to avoid all the above-described disadvantages therefore, the invention provides, for tubes provided with filling bodies, that each individual filling body is held in a predetermined position by carrier elements, which in the case of counter-current tubes are secured on the outer surface of the inner tube or in the case of single tubes are secured on an insert of rod form extending axially of the tube.

By reason of this construction every individual filling body receives sufiicient space for thermal expansion and can never be jammed in and thus destroyed. The outer tube jacket, which according to the invention is completely separated from the filling bodies and thus unstressed by them but as regards temperature is most heavily stressed, can expand and contract both in the peripheral direction and in the longitudinal direction of the tube in accordance with the temperature fluctuations occurring, without being hindered in any way by the filling material. The widenings and finally destruction of the tube jacket possible hitherto due to caking of the filling body material are thus completely precluded. Finally due to the regular and exactly determined and permanent arrangement of the filling bodies it is ensured according to the invention that equal flow conditions exist at all points of the tube, so that the progress of the process in the relevant reaction tubes is naturally influenced especially advantageously.

An especially advantageous and simple embodiment is obtained if the carrier elements for the filling bodies are formed as metallic pins welded on the inner tube or rodshaped inserts, upon which one or more annular filling bodies can be pushed. The loads to be taken up here by each individual carrier pin are so minimal that relatively thin wire pins of appropriately refractory high-grade steel can be used, without need to fear bending thereof. The provision of such carrier pins is possible in a rapid and simple manner by means of modern spot-welding guns and the fitting or threading of the individual filling bodies on to the carrier pins can also take place in a relatively short time. In any case the extra expense involved therein bears no relation whatever to the advantages explained above which are obtained with the construction according to the invention.

Naturally the carrier elements can also be formed as support elements upon which the filling bodies rest freely, in which case then the support elements are expediently formed from a plurality of support ribs or the like, between which there remain in each case gaps for the through-flow of the reaction media.

The carrier elements can expediently be secured to the inner tube or rod-shaped insert with slight downward inclination, since this achieves a more stable arrangement of the filling bodies on the carrier elements.

The individual filling bodies can be formed with a shape widening conically towards the outer wall of the tube or in the case of the association of a plurality of filling bodies with the individual carrier elements these can be made correspondingly greater with increasing radial distance, in such manner that the interspaces between the individual filling bodies remain approximately equal in the peripheral direction.

The invention will be explained in greater detail hereinafter by way of example with reference to the accompanying drawings, wherein:

FIGURE 1 is a lateral view of filling bodies secured on the inner tube of a counter-current tube unit according to the invention, the outer tube being omitted,

FIGURE 2 is a vertical along the line I-I in FIGURE 1 with outer tube,

FIGURE 3 is a horizontal section through the arrangement according to FIGURES 1 and 2,

FIGURE 4 is a perspective view of a modified filling body embodiment with associated carrier pins.

FIGURE 5 is a lateral view similar to FIGURE 1, showing a modified embodiment of filling bodies and carrier elements,

FIGURE 6 is a section along the line 11-11 in FIG- URE 5,

FIGURE 7 is a lateral view similar to FIGURES 1 and 5, showing a further variant of the embodiment of filling bodies and carrier elements, and

FIGURE 8 is a section along the line III-III in FIG- URE 7.

In the drawings, the invention is explained with reference to a so-called counter-current tube, in which the invention can be used with particular advantage, since the inner tube of such counter-current tubes can be utilized for the securing of the carrier elements for the individual filling bodies. The invention is obviously however also usable for simple tubes, in which case it is necessary to use a special insert of rod or tube form for the securing of the carrier elements, in place of the inner tube which is present in counter-current tubes.

FIGURES 1-3 show an especially advantageous form of embodiment of the invention, in which metallic carrier pins 3 are secured on the inner tube 2 of a counter-current tube unit in regular geometric arrangement so that regular interspaces are produced between annular filling bodies 4 pushed on to the carirer pins 3. In the embodiment shown in FIGURES 1-3, two annular filling bodies 4 are pushed on to each carrier pin 3, the outer filling bodies in the radial direction having a greater diameter so that the intervals between the individual filling bodies in the peripheral direction remain approximately equal. Naturally it is also possible to place further filling bodies or only one filling body on each carrier pin, depending upon the size of the annular gap between inner tube 2 and outer tube 1. Moreover the individual filling bodies can be made to widen conically towards the outer wall, in order to achieve a still better space utilization and still more regular flow conditions through constant interspaces between the individual filling bodies'in the peripheral direction.

As shown by FIGURE 4, the arrangement of the individual filling bodies 4a in accordance with the invention permits the selection of special shapings thereof which increase the effect of the filling bodies, without any danger of these filling bodies being destroyed by reason of their radial or axial bores or the like. Even profiled carrier pins 3a are usable.

The embodiments shown in FIGURES 5 to 8 are similar in principle to the embodiment according to FIGURES 1 to 4. The filling bodies 4b and 4c are merely made spherical or cylindrical in place of the annular filling bodies 4 in the embodiment according to FIGURES 1 to 4, and rest on correspondingly formed support elements 3b and 30 respectively secured on the inner tube 2. Naturally further modifications of the forms of the utilized filling bodies and of the carrier elements carrying these are also possible. It is essential only that each individual filling body is held in a predetermined position by the nature of its support and receives adequate space for movements caused by temperature, and that the outer tube jacket remains unloaded, so that it is not additionally stressed by the filling bodies. If necessary, the invention even permits utilization of filling body materials which have a chemically or physically attacking effect upon the tube material. For positive screening of the filling bodies from the outer tube jacket it is possible if desired to arrange protective caps of neutral material on the outer ends of the carrier elements. Naturally this especially facilitates the use of highly delicate tube materials, for example ceramics or quartz, for certain special purposes. For many applications, the use of such materials becomes possible for the first time, since they are poorly capable of withstanding the stresses as described above which ocour on free pouring of filling bodies.

The foregoing is a description of a preferred embodiment of the invention by way of example only and the invention is not limited to the specific features shown but contemplates all such variations as come within the spirit of the invention as defined by the following claims.

What is claimed is:

1. Reaction apparatus comprising in combination,

a tube extending generally vertically,

an axially extending support means within said tube and spaced from the wall of said tube,

spaced apart and generally radially extending carrier elements attached and supported at one end on said axially extending support means within the tube in position with respect to each other in a uniform predetermined arrangement, and

filling bodies received on said carrier elements and held in position with respect to each other in a uni- :form predetermined arrangement whereby equal flow conditions exist at all points within the tube and the weight of the filling bodies is directly carried by said carrier elements.

2. Apparatus according to claim 1 wherein the individual filling bodies have a shape widening conically towards said surrounding tube wall.

3. Apparatus according to claim 1 wherein a plurality of filling bodies are allocated to the individual carrier elements, said bodies possessing correspondingly larger dimensions with increasing radial distance, so that the interspaced between the individual filling bodies remain approximately equal in the peripheral direction.

4. Apparatus according to claim 1 wherein the axially extending support means within the tube is an inner generally concentric tube.

5. Apparatus according to claim 4 wherein the carrier elements are metallic pins welded to the outer surface of the inner tube and the filling bodies have apertures therethrough through which the pins extend.

6. Apparatus according to claim 5 wherein the metallic pins incline slightly downward toward the inner tube.

7. Apparatus according to claim 5 wherein the individual filling bodies received on said metallic pins have a shape widening conically towards said surrounding tube wall.

8. Apparatus according to claim 5 wherein the filling bodies have an aperture therethrough and a plurality of the filling bodies are allocated to the individual metallic pins, said filling bodies possessing correspondingly larger dimensions with increasing radial distance, so that the interspaces between the individual filling bodies remain approximately equal in the peripheral direction.

9. Apparatus according to claim 4 wherein the carrier elements are shelf-like members and the filling bodies rest freely thereon.

10. Apparatus according to claim 1 wherein the axially extending support means within the tube is a rod.

11. Apparatus according to claim 10 wherein the carrier elements are metallic pins having one end Welded to said rod and the filling bodies have apertures therethrough through which the pins extend.

12. Apparatus according to claim 11 wherein the filling bodies received on said metallic pins have a shape widening conically towards said surrounding tube wall.

13. Apparatus according to claim 10 wherein the filling bodies have an aperture therethrough and a plurality of the filling bodies are allocated to the individual metallic pins, said filling bodies possessing correspondingly larger dimensions with increasing radial distance, so that the interspaces between the individual filling bodies remain approximately equal in the peripheral direction.

14. Apparatus according to claim 10 wherein the carrier elements are shelf-like members and the filling bodies rest freely thereon.

15. Apparatus according to claim 14 wherein the shelflike members incline slightly downward toward the axially extending rod.

.16. Apparatus according to claim 14 wherein the indvidual filling bodies have a shape widening conically towards said surrounding tube wall.

17. Apparatus according to claim 14 wherein a plurality of the filling bodies are allocated to the individual shelflike members, said filling bodies possessing correspondingly larger dimensions with increasing radial distance, so that the interspaces between the individual filling bodies remain approximately equal in the peripheral direction.

18. Reaction apparatus in which filling bodies are regularly arranged by carrier elements, characterized in that each single filling body is held by a carrier element with sufiicient space for expansion in all directions in a predetermined position within an outer tube arranged generally vertically and having an axially extending support means spaced therewithin, said carrier elements being attached and supported at one end thereof on said axially extending support means within the tube in position with respect to each other in a uniform predetermined arrangement whereby equal flow conditions exist at all points within the tube and the weight of the filling bodies is directly carried by the respective carrier elements.

19. Apparatus according to claim 18 wherein the individual filling bodies have a shape widening conically towards the surrounding tube wall.

20. Apparatus according to claim 18 wherein a plurality of filling bodies are allocated to the individual carrier elements, said bodies possessing correspondingly larger dimensions with increasing radial distance, so that the interspaces between the individual filling bodies remain approximately equal in the peripheral direction.

21. Apparauts according to claim 18 wherein the axially extending support means within the tube is an inner generally concentric tube.

22. Apparatus according to claim 21 wherein the carrier elements are metallic pins welded to the outer surface of the inner tube and the filling bodies have apertures therethrough through which the pins extend.

23. Apparatus according to claim 22 wherein the individual filling bodies received on said metallic pins have a shape widening conically towards said surrounding tube wall.

24. Apparatus according to claim 22 wherein the filling bodies have an aperture therethrough and a plurality of filling bodies are allocated to the individual metallic pins, said filling bodies possessing correspondingly larger dimensions with increasing radial distance, so that the interspaces between the individual filling bodies remain ap- References Cited proximately equal in the peripheral direction. UNITED STATES PATENTS 25. Apparatus according to claim 18 wherein the axially extending support means within the tube is a rod. 312831028 11/1966 Bergstrom et 23-277 26. Apparatus according to claim 24 wherein the car- 5 3,280,907 10/1966 Hoffman 165185 rier elements are metallic pins welded to the rod and the 3,154,386 10/1964 Lefren 23 277 filllling bodies gave apertures therethrough through which FOREIGN PATENTS e Pmscxten 116 547 2/1943 Australia 27. Apparatus accordmg to clalm 24 wherein the car- 783,521 9/1957 Great Britain.

rier elements are shelf-like members having an end sup- 10 ported by said rod and the filling bodies rest freely JAMESH TAYMAN JR Primary Examiner thereon. 

